Beefing up some muscles doesn’t take steroids or exercise — paraffin wax will do. Incorporating wax into artificial muscles spun from carbon nanotubes gives them superior flexing power, a discovery that could lead to smart materials such as fabrics that respond to environmental changes.

The new artificial muscles, about twice the diameter of a human hair, can lift 175,000 times their weight, outperforming mammalian muscles and all previously made artificial muscles (SN: 12/4/10, p. 20), a ...